A new liquid chromatographic method for routine determination of oxytetracycline marker residue in the edible tissues of farm animals

Abstract

A simple, rapid, and specific ion-pair liquid chromatographic method for routine determination of the marker residue of oxytetracycline (OTC), namely OTC and 4-epi-oxytetracycline (4-epiOTC), in edible animal tissues (muscle, liver, kidney, and fat) has been developed. Minced tissue samples were acidified at pH 2.7 with 2 mol L(-1) sulfuric acid and extracted with acetonitrile. The extracts were purified by treatment with ammonium sulfate solution and concentrated into 0.1 mol L(-1) phosphoric acid. Baseline separation was carried out isocratically on a Nucleosil 100-5 C(18), 5-microm column using an acetonitrile-0.01 mol L(-1) disodium hydrogen phosphate (20:80, v/v) mobile phase that contained both positively (tetrabutylammonium) and negatively (octanesulfonate) charged pairing ions and EDTA, and was adjusted to pH 3.8. Detection was by UV at 370 nm. The method was fully validated according to Commission Decision 2002/657/EC. Overall recoveries were better than 82.6% and overall relative standard deviation was better than 6% for all the tissues examined. The good analytical characteristics of the method allowed limits of quantification as low as 30 ng g(-1) for muscle and fat and 50 ng g(-1) for liver and kidney, for both OTC and 4-epiOTC, to be realized. The method was successfully used to determine the OTC marker residue in tissues of two sheep intramuscularly administered a commercial OTC formulation.

Liquid chromatographic determination and depletion profile of oxytetracycline in milk after repeated intramuscular administration in sheep

“…Use of an acidic solvent is of great assistance in overcoming this difficulty [12,14,15,17,19], but low recovery has been usually reported. To overcome this problem, extraction of milk samples with 2 volumes of acetonitrile was used, and this resulted in protein precipitation but extraction of OTC and 4-epiOTC was not quantitative unless milk samples had been acidified at pH values lower than 3 [20]. This could be possibly due to incomplete dissociation of non-covalently bound OTC and 4-epiOTC from milk proteins at higher pH values.…”

“…The former objective was effectively realised in view of using simple LC-UV/visible equipment to develop a simple, rapid, specific and cost-effective LC method based on a recently published LC method [20] concerning the determination of OTC residues in animal tissues, with some modifications. The latter objective was accomplished via a large scale experiment with 20 healthy sheep intramuscularly injected with a conventional OTC formulation.…”

Current trends in sample preparation for growth promoter and veterinary drug residue analysis

“…Examples of the successful application of ion-pair extraction are β-agonists [58], aminoglycosides [59] and oxytetracycline [60]). …”

Man-tailored biomimetic sensor of molecularly imprinted materials for the potentiometric measurement of oxytetracycline

“…Analytical procedures suggested in the literature for OXY detection and quantification regard microbiological methods (Jevinova et al, 2003;Gesche et al, 2001;Piriz et al, 2001;Myllyniemi et al, 2000;Okerman et al, 2001;Tantillo et al, 1997;Markakis, 1996;Wanner et al, 1994;Hasselberger, 1993;Jinbo et al, 1992;Roudaut et al, 1987;Muellerbrennecke et al, 1980) or liquid-chromatographic techniques (Khosrokhavar et al, 2008;Fletouris and Papapanagiotou, 2008;Maia et al, 2008;Kowalski and Pomorska, 2007;Biswas et al, 2007;Fritz and Zuo, 2007;Miller et al, 2007;Kowalski et al, 2006;Hosseini et al, 2006;Poapolathep et al, 2008;Yegorova et al, 2006;Pena et al, 2005;Rupp and Anderson, 2005;Lu et al, 2004;Schneider et al, 2007;Kim et al, 2006). The former is unsuitable for routine control procedures considering that each trial may take several days, and analytical laboratories also require proper facilities to handle biological compounds safely.…”